docs: def _tokens_from_patsy(node):
      """
      Yields all the individual tokens from within a patsy formula
      as parsed by patsy.parse_formula.parse_formula.
  
      Parameters
      ----------
      node : patsy.parse_formula.ParseNode
  
      """
      for n in node.args:
          for t in _tokens_from_patsy(n):
              yield t
  
      if node.token:
          yield node.token